Actuators are integral devices in building automation systems, including heating, ventilation and air conditioning (HVAC) systems. Actuators can be used to rotate chilled water or steam valves, and to open and close ventilation dampers. Dampers can be used for general comfort control as well as for laboratory safety ventilation.
In particular, with regard to dampers, ventilation dampers of HVAC systems control the flow of air into a room, space, air handling unit or ventilation duct or shaft. The dampers may be completely open, closed, or at varying degrees of partially open. Further opening a damper has the effect of increasing the flow of air through the damper, while further closing a damper has the effect of decreasing the flow of air through the damper. When the air flow consists of chilled air, or heated air, then the opening and closing of dampers may be used to regulate the temperature in a space.
Some ventilation dampers are manually actuated. However, building automation systems typically include automatically operated ventilation dampers, and typically large numbers of such dampers. The position of the damper (i.e. its degree of “openness”) in such a system is usually under the control of an automated controller. The controller adjusts the position of the damper based on whether more or less air flow to the room is desired.
A damper actuator is the electromechanical (or other) device that converts the control signals from the controller to the motive force that physically adjusts the position of the damper. The actuator may include a motor and gear set. In some cases, an actuator is in the form of a solenoid, or motor in combination with a mechanical bias spring. Various forms of actuators are available and suitable for use.
In addition to ventilation dampers, actuators are also used to control the operations of valves in HVAC systems. A valve actuator is similar to a damper actuator in that it converts control signals into a motive force the physically adjusts the position of the valve, thereby admitting a controlled flow of chilled water, steam or other liquid through an orifice.
One issue arising from the use of dampers and valves is the cost and time required for installation. Because dampers and valves are typically outside an occupied space, such as in the plenum (i.e. above the ceiling) of rooms and hallways, installation is at best inconvenient. Moreover, because actuators must be able to receive control signals and employ electrical power, each actuator requires cabling and coupling to new or existing communication and/or power circuits.
There is a need to reduce costs associated with installing actuators in an HVAC system.